Plant Doctor Archive

What can I plant in my clay soil?

I have a corner of my section which has heavy clay soil with poor drainage. I have applied compost for about three years now and the soil is beginning to show signs of improvement. However, I am looking for a suitable tree to grow in these conditions, preferably an evergreen as we hope to put a pool in this area in the near future.

Without knowing how high you would like the tree to grow and whether the area is frost prone, here are a few suggestions.

Magnolia grandiflora grows to about 7 metres high, is slow growing, has spectacular creamy-white, fragrant flowers. Magnolia grandiflora "Little Gem" also has lovely creamy-white flowers and only grows to a height of 3 metres. Both have lovely foliage.

Sophora microphylla (Kowhai) — there are several varieties growing from 1.2 metres up to 5 metres. However, the flowers do drop and could become a problem when the pool is installed.

Pseudopanax (Lancewood or Five Finger) — another evergreen NZ native which is extremely hardy. There are variegated forms to add interest.

Metrosideros (Pohutukawa) — various cultivars are available, including yellow flowered and variegated forms. Which variety you choose would depend upon the final height you want it to grow to.

Gordonia axillaris may also be a possibility. It has lovely creamy-white flowers and clusters of yellow stamens. It flowers in winter and grows to a height of 3 metres. Gordonias are slow growing.

Grevillea — there are several varieties of Grevillea that grow from 2 to 3 metres in height. They have attractive spider-like flowers and are extremely hardy.

Griselinia littoralis or G. lucida — NZ natives worthy of a look.

Cupressocyparis leylandii is a fast growing conifer with attractive foliage. Grows to a height of 5 metres.

This list is by no means comprehensive and is only a starting point — your local garden centre can help with trees suited to your local conditions.

It may be worth looking at planting into a raised bed to improve drainage, or using gypsum to help break down the clay soil. Gypsum comes in a powder form, is a type of lime and is also available in a liquid form.

Meanwhile, keep adding compost, peat or as much well-rotted organic material to the soil as you can.

Advice by Dr Dan Blanchon from Unitec's Diploma in Sustainable Horticulture and Bachelor of Resource Management.

Reproduced with permission from NZOOM Home and Garden content, from the previous website of  The views expressed here are not necessarily those of the RNZIH   HOME AND GARDEN   Plant Doctor Archives Main Page